Sound-producing apparatus or electromagnetic receiving or emitting device



M. GuERrroT' SOUND PRODUCING APPARATUS OR ELECTROMAGNETIC RECEIVING 0R EMITTING DEVICE Filed A i-il' 12, 1922 flttorrveys Patented Jan. 113, 1925.

v saaaea PATENT oration.

MAURICE GUERITCT, or PARIS, FRANCE, ASSIGNOR 'ro soCIE'rE nEs ETABLISSE- MENTS GAUMoNT, or rams, FRANCE.

SOUND-PRODUCING APPARATUS 0B.

ELECTROMAGNETIC RECEIVING on. EMITTING DEVICE.

Application filed April 12, 1922. Serial No. 551,802.

mitted to the diaphragm by a light rod and produced by the armature of an electro-m agnet or by a coilidisposed in the field of a magnet and employed after the manner of a galvanometer coil. This invention relates to an apparatus for the production of sounds essentially comprising a vibrating diaphragm which is constituted together with suitable turns of a conducting wire which are juxtaposed and imbedded in the mass thereof. The diaphragm as a whole is submitted to the action of a magnetic field, and the shape of the diaphragm as well as the direction of the magnetic field are so combined that when a tele, phonic current is sent into the conducting Wire entering into the composition of the said diaphragm the latter is caused to vibrate and will reproduce the sounds.

This new disposition will afford diaphragms of a very light construction to which very considerable forces can be applied in spite of their small mass. Further more, and this advantage is appreciable as concerns the quality 'of the sound produced,

the motive force is set up directly and equally at all points of the diaphragm. Inasmuch as the motive force is produced at each point where it is consumed and is not; transmitted from one point to the other of the diaphragm, this will afford the construction of acoustic diaphragms of larger sizes than are obtained by the known methods.

The following description, together with the accompanying drawings which are given by way of example, sets forth various em bodiments of the invention.

, Fig. 1 is a diagrammatic viewof an explanatory nature.

Fig. 2 is a form of construction of an electro-magnetic receiver.

Fig. 3 is a perspective view of the diaphragm. I

Figs.-4and 5 are modified. forms of construction of the receivers or electro-magneticemission devices.

. The reproductionof the sounds according to the invention can only be obtained by a special arrangement of the diaphragm and the magneticfield. This essential arrange ment will be examined in its general principles before proceeding with a description of the apparatus based upon the same.

Fig. l represents two segmentsA and B forming part of the pole-pieces of a magnet. The air-gap between Aand B is made narrow, so that in the air the magnetic'force H is substantially perpendicular to the two parallel surfaces on either side of the airgap. An element Gofthe diaphragm is shown between A and B, and if the air-gap is narrow, it must necessarily be parallel to the adjacent pole surfaces. A portion of'a con-' ducting turn MN is disposed upon the ele ment Gr ofdiaphragm surface as above set forth. When acurrent i is sent through theconductor, the portion MN of the latter having a' length "Z is submitted to a force 7' Whose value in the field having an intensity H is given by the formula Y fzZHi This force is perpendicular to to H.

Should the said turn, drawing with it the element of surface adhering thereto, yield to this force and move in the sense of the latter, thus employing the force to the maxi-" mum extent, the element of the diaphragm Gr would be caused'to move in its own plane, thus sliding upon itself. In these conditions it would exert no pressure upon the air and would produce no acoustic effect. The sound will have the maximum value if the element of the diaphragm is caused to move perpendicular to its own plane. But in this event the motion will be perpendicular to the motive force f. For this motion, the

MN as well as motive force .WOlllCl lose all its eilicacity. It

f ziZH coso:

It will effect a displacement of the element G of area 8 by an amplitude A00 in the di- 'reotion X. -The acoustic effect, which is measured by the volume of air displaced, is in-this case WzsAm sina As observed, it is required for the .operation of the device that neither the useful component of the force nor the volume of air displaced shall be null, and this will pre, vent giving to o: the values 0 or 90 It is preferable to give values to 0: which are near but this particular value1s not essential.

As an example of a diaphragm based upon this principle, the device may com prise a diaphragm having the form of a cone of revolution with an angle near 45 at the apex and disposed in an air-gap bounded by two conical coaxial surfaces having the same angle. The turns of conducting wire are disposed in spirals'approximately representing circles parallel to the base of the cone, and the diaphragm will move in 'the axial sense under the action of a current sent into the conducting wire.

The said conical form is not an essential feature of the invention, as is set forth in the detailed description which precedes.

' The conical form is simply the one which may be produced with the greatest facility among the arrangements in conformity to the principle of the invention. It will be equally advantageous to construct diaphragms having the form of a surface of revolution which do not differ appreciably from the conical form, but it is obvious that the surface need not be a surfaceof revolution in order to obtain the desired effect.

Fig. 2 is an axial section of an electromagnet of the ironclad type. Between the pole-pieces A and B is provided a narrow air-gap D E G which is formed according to the above-mentioned principles. It is bounded by two parallel surfaces ofrevolution which differ but little from the conical form. The diaphragm has the same shape .as the surfaces bounding the air-gap within which it is disposed, and is represented separatel in the perspective view Fig. 3. As w1ll e observed, it is provided with a coil'of wire whose terminals are at K and. L, the said. coil being of somewhat spiral" shape wherein the turns do not differ apmay be place preciably from circles which may be drawn produces a very strong magnetic field in the air-gap. Upon sending a. telephonic current into the wire disposed "on the said diaphragm, the latter will be set in vibration parallel to its axis ofrevolution, and the sound will be produced in the space between the. diaphragm and pole-pieces. Suitable ducts formed in the pole-piece A are used to convey the sound produced upon the concave side of the diaphragm to a passage 10 having disposed therein the mouthpiece o for projecting the sound at a distance.

Fig. 4 shows another arrangement according to the principle of-the invention. In

this case the mouthpiece is eliminated, the

diaphragm acts by its convex surface and the sound proceeds directly into the air' without mouth-piece through the apertures formed in the pole-piece A.

In the device shown in Fig. 5, the air-gap is provided in the external wall of the ironclad electromagnet, but the operation remains the same as in the preceding cases, the diaphragm being of annular shape in this device.

In thevarious apparatus hereinbefore described the magneticfield is produced by an electro-magnet, but it is obvious that the magnetic field maybe produced in like manner by one or more permanent magnets. Each of the said apparatus contains but a single diaphragm, but it is evident that a plurality of diaphragms according to the invention useful may be disposed in the same air-gap or in wire disposed in a singlelayer, but it maybe found useful to form awinding of a plurality of superposed layers.

in contact or separated, or again wound in a number of distinct circuits. The winding may be carried out with wire of any suitable'material such as copper, aluminum or magnesium. The wire may be of cylindrical or other shape, and it may be advantageous to make use of a conductor in the form of a ribbon. The insulation between theturns can be obtained by any suitable process.

The material of the dia hragm may be of The turns any adequate substance, either rigid, elastic or soft, and the diaphragm can be construct ed for example by causing the wire to adhere to the surface of cloth fabric, paper or It may be preferable to weavethe the like. said. wire with a textile thread, so as to form a sort of fabric; the turns of wire could furthermore be covered and connected together by disposing thereupon a solution of collodion, rubber or like substance. This description of the methods of construction of the liaphragm is not however of a limitative nature.

The said diaphragm may be inserted upon its edge in a rigid or a flexible manner, or

' may be supported at various points in any sufficient number. Should it be desired, the weight of the diaphragm can be equilibrated by an electric current sent into the winding. The diaphragm can be used not only to produce sounds in the air, but may also be employed under water so as to emit the sounds in the water. In this event the water may come in contact with both sides of the same, or only one side.

The said devices may be supplied with telephonic current from any suitable source that can be used for all purposes requiring the emission of sounds. The hereinbefore described apparatus are of the reversible type; if a sound should strike against the diaphragm it is caused to vibrate, and its motion in the magnetic field will induce a current in the wire' disposed thereupon. This current may be utilized in the same manner as the current from a microphone, whether the said apparatus be employed in the air or under water.

What I claim is: v

1. An apparatus for the emission and reception of sound constituted by a magnet, a wire winding on a support,'said wire haw ing, therein a variable current )produced by the acoustic displacements or being capable of producing such displacements, said winding representing at the same time a mechanical element receiving or emitting .vibrations and an electromagnetic element producing or receiving the variable current, said element being disposed in the air-gap of the magnet in such manner that the direction of vibration of the wire winding 011 a support, as a whole, shall be oblique to the direction of the magnetic field of the 2. An apparatus for air-gap, whereby all points of the wire winding on a support, as a whole, shall be caused to vibrate upon the passage of the current, thus producing a loud sound in a direct manner and without any other means.

the emission and re-' ception of sound constituted by a magnet,

comprising two pole piecesof conical shape respectively convex and concave, a wire winding on a conical support, said wire havmg therein the variable currentv produced by the acoustic vibrations or set up by the I same, said winding constituting at the same time the mechanical element emitting or receiving the vibrations and the electromagnetic element emitting or receiving the variable .currents, said winding being disposed in the air-gap of the magnet and parallel to the faces of the said air-gap whereby the displacement of the wire winding on a support as a whole, which occurs parallel to the axis, is oblique to the direction of the magnetic field and whereby all the points of the wire winding on a support as a'whole shall be caused .to vibrate upon the passage of the current, thus producing a loud sound in a direct manner and without any other means.

3. An apparatus for the emission andreception of sound constituted by a magnet comprising two pole pieces whereof one is apertured in order to facilitate the trans mission of vibrations to the surrounding air, a support having dlsposed thereon a wire coil and disposed in the air gap of the magnet in such manner that the direction of vibration ofthe diaphragm shall be oblique to the direction of the magnetic field of the air gap, whereby all points of the diaphragm shall be caused to vibrate upon the passage of the current, thus producing a loud sound in' a direct manner and without any other means.

In testimony whereof I have specification.

MAURICE GUERITOT.

signed this 

